nes-proj/cpu/z80/mtarch.c

193 lines
4.7 KiB
C

/*
* Copyright (c) 2007, Takahide Matsutsuka.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/*
* \file
* Z80 machine-specific implementation for supporting multithread.
* \author
* Takahide Matsutsuka <markn@markn.org>
*/
#include "sys/mt.h"
#include "mtarch.h"
/*--------------------------------------------------------------------------*/
void
mtarch_init(void)
{
}
/*--------------------------------------------------------------------------*/
void
mtarch_start(struct mtarch_thread *t,
void (*function)(void *), void *data)
{
u16_t i;
for(i = 0; i < MTARCH_STACKSIZE; i++) {
t->stack[i] = i;
}
t->sp = &t->stack[MTARCH_STACKSIZE - 1];
/* A parameter for method for thread function. */
*t->sp = (u16_t)data;
--t->sp;
/* This will be a return address of thread function. */
*t->sp = (u16_t)mt_exit;
--t->sp;
/* The thread function, is used as a return address of mtarch_switch. */
*t->sp = (u16_t)function;
--t->sp;
/*
* Space for registers.
* af, bc, de, hl, ix, iy, af', bc', de', hl'
*/
/*
* Z80 stack basis:
* push stores the data AFTER decrementing sp.
* pop reads the data BEFORE incrementing sp.
*/
t->sp = t->sp - 9;
}
/*--------------------------------------------------------------------------*/
static struct mtarch_thread *running_thread;
static u16_t *sptmp;
static void
mtarch_switch()
{
__asm
di ; disable interrupt
; normal registers
push af
push bc
push de
push hl
push ix
push iy
; back registers
ex af,af'
push af
exx
push bc
push de
push hl
; swap between running_thread->sp and SP reg
; _running_thread in asembler below points running_thread->sp
; sptmp = sp;
ld (_sptmp),sp
; sp = *(running_thread->sp);
ld ix,(_running_thread)
ld l,0(ix)
ld h,1(ix)
ld sp,hl
; running_thread->sp = sptmp;
ld hl,(_sptmp)
ld 0(ix),l
ld 1(ix),h
; back registers
pop hl
pop de
pop bc
exx
pop af
ex af,af'
; normal registers
pop iy
pop ix
pop hl
pop de
pop bc
pop af
ei ; enable interrupt
__endasm;
// here sp indicates the address that point the function
}
/*--------------------------------------------------------------------------*/
void
mtarch_exec(struct mtarch_thread *t)
{
running_thread = t;
mtarch_switch();
running_thread = NULL;
}
/*--------------------------------------------------------------------------*/
void
mtarch_remove()
{
}
/*--------------------------------------------------------------------------*/
void
mtarch_yield()
{
if (running_thread == NULL) {
/* ERROR! we have no runnning thread. */
return;
}
mtarch_switch();
}
/*--------------------------------------------------------------------------*/
void mtarch_stop(struct mtarch_thread *thread)
{
}
/*--------------------------------------------------------------------------*/
void
mtarch_pstop()
{
}
/*--------------------------------------------------------------------------*/
void
mtarch_pstart()
{
}
/*--------------------------------------------------------------------------*/
int
mtarch_stack_usage(struct mtarch_thread *t)
{
u16_t i;
for (i = 0; i < MTARCH_STACKSIZE; i++) {
if (t->stack[i] != i) {
return MTARCH_STACKSIZE - i;
}
}
return 0;
}
/*--------------------------------------------------------------------------*/